The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Recent rising oil prices have driven worldwide car manufacturers into unlimited competition to improve fuel efficiency. In addition, great efforts have been made to reduce the weight and improve the fuel efficiency of engines based on a variety of techniques such as downsizing, and similar measures.
Meanwhile, among methods utilized for transmissions equipped in vehicles to improve fuel efficiency, there is a method allowing an engine to operate at more efficient operation points using the multi-staging of a transmission, thereby improving the fuel efficiency.
Further, such the multi-staging of a transmission allows an engine to operate in a relatively low RPM (revolutions per minute) range.
However, as the number of shifting stages of a transmission increases, the number of internal parts constituting the transmission also increases. This may lead to undesirable effects instead, such as the reduced mountability and transfer efficiency and the increased cost and weight of the transmission.